Spectacled duck
| Spectacled duck | ||||||||||||
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Spectacled Duck ( Melanitta perspicillata ) |
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| Scientific name | ||||||||||||
| Melanitta perspicillata | ||||||||||||
| ( Linnaeus , 1758) |
The spectacled duck ( Melanitta perspicillata ) is a monotypical sea duck native to North America . So far there is no evidence that it also breeds in the Palearctic . However, it occasionally winters on the northern coasts of Europe. Since 1980, about 30 individuals have been observed in winter in Northern Great Britain and Ireland. Spectacled ducks can also be seen occasionally in France, Denmark, Norway and Finland.
External features
The spectacled duck is 46 to 55 cm long, weighs 800 to 1200 g and has a wingspan of 90 cm. It has a black plumage, only the males are conspicuously marked on the head by two white spots and a black-white-red beak. The plumage of the males is a little less shiny than is the case with the common scoter belonging to the same genus . The feet of the males are red, the eyes outlined in white. Similar to the plush head duck , the spectacled duck also has a bill shield and the head profile is wedge-shaped. When the male is resting, the color of the beaks is less contrasting. The body plumage is soot-black. The white patch on the neck is still there, but the white patch on the head is not.
The female is completely blackish-brown except for two lighter spots on each side of the head. The body is slightly darker than the head and neck. Their beak is dark gray. The legs and feet are yellow-orange. The iris is white. When resting, their plumage is rather uniformly black-brown. Young birds have the same plumage as the female.
In flight the spectacled duck resembles the common scoter , although spectacled ducks are slightly larger. The female of the spectacled duck can also be confused with the female of the eider when swimming on the water . Compared to the velvet duck, the spectacled duck is also somewhat larger and the males lack the white sections on the wings, as is characteristic of velvet ducks. Spectacled ducks often migrate in large flocks. The altitude is very low over the open sea. Overland, on the other hand, they fly significantly higher and are noticeable due to their abrupt change of direction.
Spectacled ducks are usually very quiet birds. Brooding males let out a low whistle and sharp puk-puk calls. The female calls guttural krraak-krraak during courtship . The young birds are warned of dangers by her with a sharp craah .
distribution
The breeding area of the spectacled duck extends from central Alaska towards the north to the banks of the Mackenzie . In the east it extends to the Hudson Bay and Central Labrador. In the interior of North America, the breeding area of the spectacled duck overlaps that of the velvet duck . However, spectacled ducks are around 10 times more common than velvet ducks. Although no subspecies are described for this species of duck, the range is disjoint .
In the winter months spectacled ducks can be found both on the coasts of the Pacific and the Atlantic and can also be observed on the Great Lakes during this time. In its eastern range, it winters as far as Baja California. For the Pacific population, California and Baja California are even the most important wintering areas. The spectacled duck occurs regularly in winter in Scotland and Norway ( Trondheimsfjord ).
habitat
The spectacled duck breeds on shallow small to medium sized lakes in open boreal coniferous forests. It prefers areas with high groundwater levels. During the wintering season it stays in the coastal waters. As a rule, they do not move more than a kilometer from land and are mostly in waters with a depth of less than 10 meters. She often uses coasts with strong surf.
food
The spectacled duck feeds on mollusks , mussels , crustaceans , insects and aquatic plants. During the breeding season, these are freshwater species. In the winter months and during the moulting season, it also stays in the coastal waters, where it mainly eats mussels. Eating swarms often dive synchronously.
Reproduction
Breeding pairs already form during the wintering phase and the courtship continues until it arrives in the breeding areas. It is a group courtship in which small groups of males seek the proximity of one or more females. The females are aggressive towards undesired males. The copulation takes place in the water; the couples separate themselves from the other spectacled ducks. The breeding pairs spread widely over the breeding area. Usually there is only one breeding pair in a body of water. The eggs are laid in the last weeks of May, usually just one week after arrival in the breeding areas. The eggs are cream-colored and weigh about 62 grams. A clutch consists of an average of 7.6 eggs. It only breeds the female. The pair bond of the male decreases significantly in the first days of breeding. They usually leave the breeding female during this time.
The nest is near the water, but mostly a few meters from the shore. It's well hidden between undergrowth and is often found under overhanging branches of conifers. The hatching time of the downy chicks falls in the last June to the first weeks of August. The peak of hatching is usually the second week of July. The downy chicks flee the nest and, led by the female adult, usually leave the nest within 24 hours. They can feed themselves, and do so by diving for food in shallow water. The young birds remain in the family unit until they fledge. The aggressiveness of the female adult against juvenile birds of the same species is one reason why the different flocks of young ducks do not mix.
Duration
For this species of duck that breeds in the far north, there are only insufficient numbers available. The IUCN estimates the number of sexually mature individuals of this species to be between 250,000 and 1.3 million. It classifies the species as 
(= least concern - not endangered), because the distribution area is very large. Overall, a decreasing population trend is observed, especially in North America, but because of the nearctic distribution of this species, only fifty percent of the North American distribution area was investigated.
Spectacled duck and human
The spectacled duck is hunted by the indigenous population in both northern Canada and Alaska (subsistence hunt). This is allowed in both Canada and the United States. As more and more duck species are being protected from this type of hunting by bans, the hunting pressure on this species is increasing.
In November 2007, an oil spill in San Francisco Bay killed thousands of spectacled ducks. About 40 percent of the Pacific population was affected by this oil spill. According to statements by scientists, this oil spill did not lead to a critical endangerment of the population of this species. However, it did affect the population as a whole, since mostly healthy, adult birds were affected, which must be included in the breeding population.
supporting documents
literature
- John Gooders and Trevor Boyer: Ducks of Britain and the Northern Hemisphere , Dragon's World Ltd, Surrey 1986, ISBN 1-85028-022-3
- Janet Kear (Ed.): Ducks, Geese and Swans. Oxford University Press, 2005, ISBN 0-19-854645-9 .
- Hartmut Kolbe; Die Entenvögel der Welt , Ulmer Verlag 1999, ISBN 3-8001-7442-1
- Richard Sale: A Complete Guide to Arctic Wildlife , published by Christopher Helm, London 2006, ISBN 0-7136-7039-8
Web links
- Melanitta perspicillata in the endangered Red List species the IUCN 2008. Posted by: BirdLife International, 2008. Accessed on December 18 of 2008.
- Videos, photos and sound recordings on Melanitta perspicillata in the Internet Bird Collection
- BirdLife factsheet on the spectacled duck
Individual evidence
- ↑ Hans-Günther Bauer, Einhard Bezzel and Wolfgang Fiedler (eds.): The compendium of birds in Central Europe: Everything about biology, endangerment and protection. Volume 1: Nonpasseriformes - non-sparrow birds , Aula-Verlag Wiebelsheim, Wiesbaden 2005, ISBN 3-89104-647-2 , p. 132
- ↑ Sale, p. 126
- ↑ Kear, p. 713
- ↑ Gooders and Boyer, p. 131
- ↑ Gooders and Boyer, p. 132
- ↑ Kear, pp. 712 and 713
- ↑ Kear, p. 713
- ↑ Kear, p. 714
- ↑ BirdLife Factsheet on the Spectacled Duck , accessed December 14, 2010
- ↑ Kear, p. 714
- ↑ San Fran oil spill hurts Canadian sea duck population . CBC News. November 23, 2007. [1]